How did the United States support the war before sending troops to Europe?

Carried supplies and war materials to the Central Powers. Invested $4 billion in European war bonds

Carried supplies and war materials to the Allies. Invested $2 billion in European war bonds

Carried supplies and war materials to the Axis. Invested $6 billion in European war bonds

Carried supplies and war materials to the Allies. Invested $8 billion in European war bonds​